This invention relates to a vertical type machining center, restricting a width in its right/left direction (a X-axis direction).
In such kind of a machining center, a workpiece is fixedly positioned on a table, and a tool is attached to an lower end of a vertical spindle, and the workpiece and the tool are three-dimensionally (in three axes directions) moved, relative to each other when machining the workpiece. That is, the machining center is for executing machining on a workpiece by relatively moving a tool in a X-axis direction (in a right/left direction), in a Y-axis direction (a front/rear direction) and in a Z-axis direction (an up/down direction) with respect to a workpiece.
Referring to the relative movement in the X-axis direction of the above-mentioned movements in the three axes directions, it is general to relatively move a table in the X-axis direction, without moving a tool (a spindle) (see Japanese patent application: publication number 2000-158217).
But, it is difficult to make the width of the whole machining center in the X-axis direction (the right/left direction) shorter if it has a structure of moving the table in the X-axis direction. In other words, the problem of such kind of machining center is that it is difficult to make the width of the whole portion shorter.
This point of problem is now explained, referring to FIG. 4(a), (b). In this case, a hole Hi is formed near a left end portion of a workpiece A, the maximum width to be machined in the X-axis direction of which is Wmax, and thereafter, a hole H2 is formed near a right end portion thereof.
Firstly, the workpiece A is positioned and fixed on a table 100. As shown in (a), the table 100 is moved in a positive direction of the X-axis direction so that the portion of the workpiece A to be machined is positioned under a tool 102 which is attached to a top end (lower end) of a spindle 101. Then, the hole H1 is formed by moving the spindle 101 in a negative direction of the Z-axis. Thereafter, the table 100 is moved in the negative direction of the X-axis so that the portion of the workpiece A to be machined next is positioned under the tool 102. Then, the hole H2 is formed by moving the spindle 101 in the negative direction of the Z-axis, as shown in (b).
At the time of forming of the hole H1, almost the whole workpiece A is positioned on the right side of the spindle 101, as shown in FIG. 4(a). On the other hand, at the time of forming of the hole H2, almost the whole workpiece A is positioned on the left side of the spindle 101, as shown in FIG. 4(b) That is, the workpiece A moves within almost twice that of the maximum machining width Wmax along the X-axis direction. For this reason, the width of the whole machining center in the X-axis direction is at least 2 Wmax, so that it is impossible to make the width shorter. This means that the width of the whole in the X-axis direction is very long when arranging a plurality of machining centers in the X-axis direction in a line.
Under this circumstance, the machining center having shorter width in the X-axis direction is desired. Furthermore, it is desired to solve problems at the time when arranging a plurality of machining centers (such as three or more), having shorter width in the X-axis direction, in a line in the X-axis direction, such as their maintenance, tool exchange and dealing with chips.